another XJ MC upgrade thread

So the E350 MC swap seems to be great for earlier XJ's running the single diaphragm brake booster. Another option for the eariler XJ's is to upgrade to a dual diaphragm booster.

The info I'm having trouble finding is re the later year XJ's w/the dual diphragm boosters. I've seen references to '95 or '98 Dodge 3500 MC's as an upgrade, but no one w/a later yr XJ that can confirm. What some are saying is that the 1 ton Dodge reservoir is too tall and people have hood clearance issues. Apparently if you have the earlier yr XJ's and run the dual diaphragm booster as an upgrade, THEN add the 1 ton dodge MC, it clears the hood? There's something about the later yr XJ's and reservoir hood clearance issues w/the 1 ton Dodge MC upgrade. One guy said a 3/4 ton reservoir clears, another guy said the 3/4 and 1 ton resevoirs are the same. I'll keep researching (when the frustration wears off and I feel motivated again) but if anyone has info re the later yr XJ's, please post up...

I'm running '97XJ, dual diphragm booster, soon to be chevy 1/2 ton discs on dana 60's F/R.

One thing I'm not seeing addressed re the Dodge MC upgrade, and maybe it's b/c it's a non issue, is that it appears none of the late 90's Dodge Ram's came w/rear disc brakes? So maybe this upgrade will only work for late yr XJ's who are still disc front/drum rear? What if you're running a later model XJ w/discs front/rear? or upgraded (even bigger) discs front/rear like my app?

thx

I'm doing the dodge swap at the moment and don't have the resevoir yet, but from searching and crossing part numbers at the dealer, the resevoir's are the same no matter if it's a 1/2 ton or the 3/4 ton or the 1 ton. I did notice a difference in the newer and the older resevoirs, but I haven't been able to tell if they will swap over or not. I can tell you that the dodge MC looks like it will bolt right up with an adapter for the push rod, but like I said, I don't know yet. The brake lines are the same for the 98-00 dodge as the 99xj's, so it's bolt on as far as that is concerned as well. I have dana 44's F/R with disc's F/R and I'll keep you posted on what it turns out like.

1999 Jeep Cherokee MC, M10-1.0 M12-1.0 lines 1" bore MC




1999 Dodge Dakota and Durango MC, 1 1/8" bore, M10-1.0
M12-1.0 lines



1999 Dodge Ram 1500, 2500, 3500 MC 1 1/4" bore, M10-1.0 M12-1.0 lines





The Van and Wagon models have a 1 1/4 bore, but appear to have a shorter MC, so I don't know how useful they would be for our application.



The 1998- March 2001 dodge trucks have the same MC. The went to a larger bore after March of 2001 it appears and they had a different line size on the earlier MC's, but the bore was the same at 1 1/4". I think that the best bet for us is going to be the 1998-2000 MC's, but I think the only hurdle is going to be the resevoirs. I haven't had a chance to look at the durango or the dakota MC's yet, but they might be a better option if you only need a small upgrade in volume with their 1 1/8" bore. I'll run over to Napa and have them pull one so I can look at it and I'll get back to you, but it looks like you might not need an adapter for the Durango and the Dakota MC's, but we'll definately need one for the Ram MC.

Ok, just got back from Advance Autoparts and the Durango/Dakota MC is virtually identical to the Jeep XJ MC. It has a different resevoir and resevoir roll pin tabs, but the mounting holes for the MC are identical as well as the push rod spacer. If you only need 1/8" more fluid volume (or if the 1 1/4" bore is too large for you resulting in a hard pedal) this is the best swap I think. If the resevoir fits under your hood that is. Swapping the XJ MC resevoir and the Durango resevoir is not doable as the spacing isn't correct.



Just for reference, it appears that up until 1999, the E-350 MC has two options, below 9500lbs GVW has a 1 1/16" MC and above 9500lbs GVW has a 1 1/8" MC. Correct me if I'm wrong, but that's what it appears. 1999 and newer has a few options and I'm not going to get into them, but they were mostly 1.3.....+" bore MC

Wow, that is great info, thank you! So which MC did you end up with? Dakota or Ram? 1 1/8" or 1 1/4"? I'm very curious to see how it works for you...

I think the Ram's went from disc/drum to disc/disc in '02+, any idea if the '02+ MC's will bolt up? Would be ideal to have a MC that was originally engineered to run disc/disc...

I don't think it is that critical that it was specifically set up for disc/disc, as long as it pushes enough volume, or a comparable amount of volume as the disc drum set up. I ended up with the Ram MC and am getting the resevoir today, so we'll see if it fits. If not, I'll probably go to the Durango one.

Alright, the resevoir for the Durango, Dakota, and Ram are the same part number and are obviously, the same resevoirs. For the following, refer to the pictures above if you get lost. For starters, the Dodge is a bit wider of a resevoir. An XJ resevoir is about 3" tall by 5" long and 3.75" tall if you include the cap. The Dodge resevoir is about 3" tall (3.75" with the cap) and about 5" long. Seems like it will fit, however, you have to take into consideration the angle that it's mounted at. The Dodge resevoir is not designed to be mounted at an angle, so it is about 3" tall from tip to tip where as the XJ resevoir is more of a triangle shape. So what is missing on the XJ resevoir on the bottom, you can pretty much add to the top front and that's how high it's gonna sit. The part that may save us is the cap on the Dodge. It's designed with the cap towards one end, so it we mount the cap to the rear (giving us less resevoir space and therefore less fluid....might be enough, might not...) it might clear the hood. If the cap is mounted towards the front, you can get more fluid in there than required if you wanted, but you might not clear the hood. It's all still going to be trial and error, but we'll find out soon enough.


Does anyone think I can just unbolt the MC without disconnecting the lines and bend it out of the way to test fit the Dodge MC? I have to drive to work tomorrow, so if I screw this up, I'm done. Any opinions? I'd like to try and fit it, but I'm not sure how it will bolt up and I don't have a picture of the spacer I'll need yet, so I can't do the swap at this time. Unless that is of course, anyone happens to be able to describe to me what I need to do to adapt the MC. I've never seen the inside of the booster, so I don't know what I'll need to make it work. Any advice?

From what Ive read, go WJ.

Speed_racer said:

From what Ive read, go WJ.

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To be totally honest, that doesn't help this thread much. The WJ's have a MC with a 1" bore, no greater than a late model XJ. This brake stuff is so muddied up with contradicting info.....Grand Cherokees are pretty much only good to the guys looking for different proportioning valves. The difference between the XJ and the WJ (and ZJ for that matter) is the proportioning valve. The MC is the same between the two and the booster really doesn't do much in the way of volume; only pedal effort. So if you're looking to upgrade and early XJ with a single diaphram booster, that's a complete swap in my book, going to a WJ or ZJ brake system.....However, if you've upgraded axles and have therefore increased your piston size and volume, you'll need not only a prop valve change, but a larger MC as well. I appreciate you're input in the matter and yes, a WJ swap is an exellent option with only upgraded rear disc's and not a whole shooting match like a few of us have done. arty:

It freakin fits!!! Yeah!!!! arty: :yelclap:



Its VERY close, but it fits just fine in a 1999 XJ with the resevoir cap in the front. The Durango/Dakota MC/resevoir will fit a tad better as it's missing about 1" of the length as the Ram MC and they take it out near the firewall, so the resevoir is pushed back closer to the firewall than the Ram's (which is downhill and will move it further away from the hood). So freakin A it works. Now its just a matter of putting a spacer or whatever I need to get the pushrod to work as well as deciding if I need the 1.25" bore or if that will be too much fluid for me. I sure hope not. We'll see as soon as I figure out what this spacer needs to look like!

awesome....

when you figure out the spacer...will you shoot a pic of it?

sure will. I always do!! I'm sure someone else has a picture of it, but they just aren't reading the threads they should be. It will take a few days until I get a bit more time and figure out what I'm doing, but I'll definately post up a picture and specs.

Well, after much thought, I decided to go and swap out MC's with the Durango instead of the Ram becasue of the pushrod issue as well as I thought that it would be almost too much fluid with 1/4" larger piston size. My brakes are stiff now and will stop me really fast, however, they do not lock my tires up which is good, but won't hold the Jeep when powerbraked. I have a feeling that the 5.13's might be a bit much for my brakes when I'm hitting the torque converter stall limit, but I'm overall happy with the swap. It couldn't have been easier, pull the old MC off, put the new one on, bleed everything. By the way, I have an XJ prop valve body with a ZJ piston and spring minus the O-ring if that helps at all. Any thoughts on the swap?



Pictures as promised....

OK one question is this a good upgrade for a 94. Going to a dual booster and then the dakota MC?
Or should I just go to a E350 MC?
I will be swapping in a 44/20 and will put disks at all four corners and at some point be on 35's

Andrew

I'm thinking about a '93 Grand Cherokee master/booster on my '87 Comanche. I already removed the stupid load sensor that cut my rear brakes off totally before and installed AMC Eagle rear wheel cylinders (now I can lockup much easier in the wet! Oops!) I'm also thinking of putting the CV axles (theye were new and it's a vacuum front diff with 3.73) and Knuckles, calipers, etc from the ZJ on the front.

Good idea or am I out of it?

I can't really say what will and will not work for you guys. It's all going to depend on if you need more volume. With stock stuff or ZJ stuff, you probably won't need more volume. With 1 ton stuff, I'd say its a good bet you'll need it. Just upgrading your MC WILL NOT give you better brakes with stock brake hardware. All it will do is make the pedal really stiff and annoy the hell out of you. For early Jeeps, just the booster swap seems to work really well. For late model Jeeps, the ZJ prop valve works well with disc brakes that are near stock volume. Like I said, it's all about volume when you start talking about swapping your MC. Also, I know nothing about the early Jeeps, or well, anything that doesn't look like a '99 when it comes to this. I've never messed with early brakes, so I'm not sure what will or will not fit/work.

I wanted to run this thread back up to the top. I am in serious need of some brake upgrades. I have a HPD44 front, running Ford outers, and an XJ D44 running the ZJ disk brake conversion. This is on a 96 XJ, so I am guessing I have the dual diaphragm booster already. The Jeep has 5.13 gears with a 4:1 and is hard to stop when in 4-LO. It seems to be getting increasingly worse, and I lost all brakes once when on the trails. They came back once I pumped the pedal, but that was the last straw. I plan on upgrading to either an E350 MC, or a 99 Ram 2500 MC, and a new (new stock replacement or better?) dual diaphragm booster.

My question is what is the best (easy to swap in/provides best performance)MC to use? Also, is it really THAT MUCH better over stock? Experiences? Any advice?

Thanks,
Andy

Andy in Pa. said:

I wanted to run this thread back up to the top. I am in serious need of some brake upgrades. I have a HPD44 front, running Ford outers, and an XJ D44 running the ZJ disk brake conversion. This is on a 96 XJ, so I am guessing I have the dual diaphragm booster already. The Jeep has 5.13 gears with a 4:1 and is hard to stop when in 4-LO. It seems to be getting increasingly worse, and I lost all brakes once when on the trails. They came back once I pumped the pedal, but that was the last straw. I plan on upgrading to either an E350 MC, or a 99 Ram 2500 MC, and a new (new stock replacement or better?) dual diaphragm booster.

My question is what is the best (easy to swap in/provides best performance)MC to use? Also, is it really THAT MUCH better over stock? Experiences? Any advice?

Thanks,
Andy

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You've got my exact setup and even on the downhills where I'm standing on the firewall my brakes hold just fine...

Sounds like you've either got air inside something or that MC is shot.

ECKSJAY said:

You've got my exact setup and even on the downhills where I'm standing on the firewall my brakes hold just fine...

Sounds like you've either got air inside something or that MC is shot.

Click to expand...

I have to agree with you. Its entirely possible, but since I am digging into it, I think I'll upgrade the MC and put on a new booster. The only other thing I did was I removed my prop valve and plumbed the front brakes directly, and I run an adjustable prop valve for the rear brakes. I can't imagine that this makes a difference though.

Andy in Pa. said:

I have to agree with you. Its entirely possible, but since I am digging into it, I think I'll upgrade the MC and put on a new booster. The only other thing I did was I removed my prop valve and plumbed the front brakes directly, and I run an adjustable prop valve for the rear brakes. I can't imagine that this makes a difference though.

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Sorry, forgot to toss in that I have no info on your upgrade. Might as well if you've got it apart and are willing. HOpefully someone will chime in with the info. I'm subscribing now.